.\"	$OpenBSD: SSL_CTX_set1_groups.3,v 1.2 2017/08/19 19:36:39 schwarze Exp $
.\"	OpenSSL SSL_CTX_set1_curves.pod de4d764e Nov 9 14:51:06 2016 +0000
.\"
.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
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.Dd $Mdocdate: August 19 2017 $
.Dt SSL_CTX_SET1_GROUPS 3
.Os
.Sh NAME
.Nm SSL_CTX_set1_groups ,
.Nm SSL_CTX_set1_groups_list ,
.Nm SSL_set1_groups ,
.Nm SSL_set1_groups_list ,
.Nm SSL_CTX_set1_curves ,
.Nm SSL_CTX_set1_curves_list ,
.Nm SSL_set1_curves ,
.Nm SSL_set1_curves_list
.Nd choose supported EC groups
.Sh SYNOPSIS
.In openssl/ssl.h
.Ft int
.Fo SSL_CTX_set1_groups
.Fa "SSL_CTX *ctx"
.Fa "const int *glist"
.Fa "size_t glistlen"
.Fc
.Ft int
.Fo SSL_CTX_set1_groups_list
.Fa "SSL_CTX *ctx"
.Fa "const char *list"
.Fc
.Ft int
.Fo SSL_set1_groups
.Fa "SSL *ssl"
.Fa "const int *glist"
.Fa "size_t glistlen"
.Fc
.Ft int
.Fo SSL_set1_groups_list
.Fa "SSL *ssl"
.Fa "const char *list"
.Fc
.Ft int
.Fo SSL_CTX_set1_curves
.Fa "SSL_CTX *ctx"
.Fa "const int *clist"
.Fa "size_t clistlen"
.Fc
.Ft int
.Fo SSL_CTX_set1_curves_list
.Fa "SSL_CTX *ctx"
.Fa "const char *list"
.Fc
.Ft int
.Fo SSL_set1_curves
.Fa "SSL *ssl"
.Fa "const int *clist"
.Fa "size_t clistlen"
.Fc
.Ft int
.Fo SSL_set1_curves_list
.Fa "SSL *ssl"
.Fa "const char *list"
.Fc
.Sh DESCRIPTION
.Fn SSL_CTX_set1_groups
sets the supported groups for
.Fa ctx
to the
.Fa glistlen
groups in the array
.Fa glist .
The array consists of group NIDs in preference order.
For a TLS client, the groups are used directly in the supported groups
extension.
For a TLS server, the groups are used to determine the set of shared
groups.
.Pp
.Fn SSL_CTX_set1_groups_list
sets the supported groups for
.Fa ctx
to the
.Fa list
represented as a colon separated list of group NIDs or names, for example
"P-521:P-384:P-256".
.Pp
.Fn SSL_set1_groups
and
.Fn SSL_set1_groups_list
are similar except that they set supported groups for the SSL structure
.Fa ssl
only.
.Pp
The curve functions are deprecated synonyms for the equivalently
named group functions and are identical in every respect except
that they are implemented as macros.
They exist because prior to TLS1.3, there was only the concept of
supported curves.
In TLS1.3, this was renamed to supported groups and extended to include
Diffie Hellman groups.
.Pp
If an application wishes to make use of several of these functions for
configuration purposes either on a command line or in a file, it should
consider using the SSL_CONF interface instead of manually parsing
options.
.Sh RETURN VALUES
All these functions return 1 for success or 0 for failure.
.Sh SEE ALSO
.Xr ssl 3 ,
.Xr SSL_CTX_add_extra_chain_cert 3 ,
.Xr SSL_CTX_set_cipher_list 3 ,
.Xr SSL_CTX_set_options 3 ,
.Xr SSL_new 3
.Sh HISTORY
The curve functions first appeared in OpenSSL 1.0.2
and the group functions in OpenSSL 1.1.1.
Both have been available since
.Ox 6.1 .
